People are cynical because they have to be. Every single day some advert company tries to release a 'viral' ad. Also people are a bit cynical because this was on the front page with tons and tons of upvotes a year ago so we have all seen this before.

Not to mention that the thing went viral on reddit 2 years ago as well and did the normal viral video circuit of morning news stations and all that jazz. So on top of being likely a viral advertisement it is also a repost of a highly popular piece of content.